TLE1 is expressed in the majority of primary pleuropulmonary synovial sarcomas

Abstract

Pleuropulmonary synovial sarcoma (PPSS) is a rare entity, similar to synovial sarcoma of soft tissue (STSS). There are 120 published cases of PPSS, but no studies have explored the expression of TLE1. In soft tissues, it has been proven a useful marker, but in tumors of other sites, its expression has not been explored. The main objective was to study the expression and diagnostic sensitivity and specificity of TLE1 in a group of PPSS, of which the diagnosis was corroborated by fluorescence in situ hybridization confirming t(X;18) in a tissue microarray. Immunohistochemistry including TLE1, vimentin, CD99, CD56, bcl-2, AE1-AE3, EMA, CD34, CK7, CK19, calponin, and S-100 was performed on all PPSS and on 25 control cases (five carcinomas, ten mesotheliomas, and ten thoracic sarcomas). TLE1 was positive in 11 cases (73.3%); bcl-2 and vimentin in 100%; calponin and CD56 in 26.6%; CD99, CK AE1-AE3, CK19, CK7, and EMA in 80%; and S100 negative in all. The only biphasic PPSS was positive for epithelial markers only in the epithelial component. TLE1 was negative in all control cases. TLE1 is expressed in 73% of PPSS, a value inferior to that reported in STSS, but is highly specific for PPSS. TLE1 may therefore be of value in the differential diagnosis of PPSS, but should be used in a panel of antibodies.

Synovial sarcoma metastatic to the parotid gland: A possible pitfall in salivary gland fine needle aspiration cytology. Report of a case with immunocytochemical and fluorescence in situ hybridization findings

“…The different immunophenotypes observed in the case here described could also be attributed, besides to immunophenotypic “infidelity” reported in SS, also to the relative lack of epithelioid areas in the parotid lesion and to differences in the primary antibodies used on the lung tissue 5 years before and currently on the cytological samples. The recently described immunohistochemical stain for TLE1 has now entered the histologic diagnostic practice of SS because of its high concordance with the SYT translocation in extensive case series …”

Primary Pulmonary Poorly Differentiated Synovial Sarcoma: Transducer-Like Enhancer of Split 1 Immunohistochemistry as A Valuable Diagnostic Aid

“…This provides a new more specific marker for diagnosis of this rare highly aggressive neoplasm. [8] TLE-1 is a member of the groucho/TLE gene family involved in beta-catenin signaling pathway and encodes a corepressor implicated in neuronal and epithelial differentiation. [9] It has been found to be significantly expressed in synovial sarcomas with a sensitivity of 82% and specificity of 92%.…”

Unusual primary intracranial dural‐based poorly differentiated synovial sarcoma with t(X; 18)(p11; q11)

“…Immunoreaction for EMA, CK (AE1/AE3), CK7 and CK19 are diagnostically useful because these are usually absent from MPNST 16 . Recently, transducer‐like enhancer of split 1(TLE1) has been revealed to have high expression in SS, 17,18 although it is also detectable in some cases of MPNST and solitary fibrous tumor with only weak staining. Thus, TLE1 is a sensitive and specific marker for SS and can be helpful to distinguish SS from histological mimics, particularly if moderate or strong staining is observed.…”